In order to scale video image real-timely, a GPU-aided parallel interpolation algorithm was proposed. Catmull-Rom Spline algorithm for image zooming was reformed into SIMD (Single instruction, multiple data) mode according to CUDA programming model. Re-sampling of each pixel was completed by a GPU thread. Hence, time-consuming re-sampling procedure of the whole zooming process were handled by parallel threads. The proposed algorithm runs hundreds times faster than traditional algorithm in experiments, and the speed is fast enough for scaling video frames real-timely. In addition, this algorithm can be extended to solve many other image processing related problems, such as image denosing and image segmentation.